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Possible K3 Line Input Damage

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Michael Tope

Possible K3 Line Input Damage

Recently I've made some configuration changes at my remote station that
should in the end improve things. In the short term, however, it has
caused problems when working voice. Specifically I was getting feedback
if I raised the line out level on the PC too far past a certain
threshold which seem to depend on the K3 compressor settings (in case
you are wondering, yes, the K3 monitor level was set to 0). Despite
these problems, I was able to make some 40 meter SSB contacts Sunday
morning during the ARRL DX Phone contest.

On Sunday afternoon, I connected to the remote with about ten minutes to
go in the contest and heard PY0F calling CQ on 20 meters with a very
loud signal. Not having touched the settings from the night before, I
figured I would tweak the tuning on the KAT-500 and then just call him.
Things did not go well. The rig broke into audio feedback and I lost
transmit/receive control for what seemed like a forever, but was
probably in reality only about 15 seconds.

After I regained control of the rig, I power cycled the rig and then
power cycled the computer (I can do that remotely). The K3 still works
fine on CW, but I can no longer operate SSB. TeamViewer indicates I am
getting audio to the remote site, but the radio no longer responds. I've
tried both VOX and manually switching to transmit. Either way, I get
nothing. I even tried playing a local audio source on the computer at
the remote site which should have gone straight into the K3. I still got
nothing.

IS IT POSSIBLE TO DAMAGE THE LINE INPUT OF THE K3 IF IT IS OVERDRIVEN BY
A SOUNDCARD LINE OUTPUT OR DOES THE K3 SOMEHOW SELF-PROTECT? IF THE
FORMER, WHAT PART IN THE K3 SERVES AS THE "FUSE"?

I know it is premature to assume the K3 is damaged as I haven't
physically been to the remote site test the rig since the incident, but
I wanted to understand what the worst-case scenarios might look like.

Thanks & 73,

Mike W4EF.................

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gt-i

Re: Possible K3 Line Input Damage

Mike,

the input circuit "the fuse" is a transformer (T1) and two resistors
(R13, R24). If overdriven, it just goes into saturation and clips the
signal, which leads to distortion. If you have, however, the capability
to put seriously more than 1Vpp into it (like 12V?) I don't know what
happens.

Another idea: have you checked the setting "MIC SEL" is still on LINE IN?
I guess you do have acesss to the K3 Serial line, so you could use the
K3 Utility to execute macros? Here is mine to switch to LINE IN:
"MD2;MN053;UP;UP;MN255;"
I did had problems with line out in the past, and Elecratf support
digged out that it may be an equalizer setting issue for in and out. Try
resetting the RX EQ to flat.
73 gl Gernot DF5RF

Am 10.03.2020 um 00:50 schrieb Michael Tope:

> Recently I've made some configuration changes at my remote station
> that should in the end improve things. In the short term, however, it
> has caused problems when working voice. Specifically I was getting
> feedback if I raised the line out level on the PC too far past a
> certain threshold which seem to depend on the K3 compressor settings
> (in case you are wondering, yes, the K3 monitor level was set to 0).
> Despite these problems, I was able to make some 40 meter SSB contacts
> Sunday morning during the ARRL DX Phone contest.
>
> On Sunday afternoon, I connected to the remote with about ten minutes
> to go in the contest and heard PY0F calling CQ on 20 meters with a
> very loud signal. Not having touched the settings from the night
> before, I figured I would tweak the tuning on the KAT-500 and then
> just call him. Things did not go well. The rig broke into audio
> feedback and I lost transmit/receive control for what seemed like a
> forever, but was probably in reality only about 15 seconds.
>
> After I regained control of the rig, I power cycled the rig and then
> power cycled the computer (I can do that remotely). The K3 still works
> fine on CW, but I can no longer operate SSB. TeamViewer indicates I am
> getting audio to the remote site, but the radio no longer responds.
> I've tried both VOX and manually switching to transmit. Either way, I
> get nothing. I even tried playing a local audio source on the computer
> at the remote site which should have gone straight into the K3. I
> still got nothing.
>
> IS IT POSSIBLE TO DAMAGE THE LINE INPUT OF THE K3 IF IT IS OVERDRIVEN
> BY A SOUNDCARD LINE OUTPUT OR DOES THE K3 SOMEHOW SELF-PROTECT? IF THE
> FORMER, WHAT PART IN THE K3 SERVES AS THE "FUSE"?
>
> I know it is premature to assume the K3 is damaged as I haven't
> physically been to the remote site test the rig since the incident,
> but I wanted to understand what the worst-case scenarios might look like.
>
> Thanks & 73,
>
> Mike W4EF.................
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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Bob McGraw - K4TAX

Re: Possible K3 Line Input Damage

Although in this case as they say, "the horse is out of the barn, and
it is too late to close the doors". This is the main reason, before I
do any configuration changes, I always make a backup of the
configuration. Using the K3 Utility, this is so easy to do. Thus
taking this extra step has saved my proverbial butt several times.

If you have an earlier configuration saved, then use the utility to
restore that configuration.

73

Bob, K4TAX

On 3/10/2020 1:08 PM, [hidden email] wrote:

> Mike,
>
> the input circuit "the fuse" is a transformer (T1) and two resistors
> (R13, R24). If overdriven, it just goes into saturation and clips the
> signal, which leads to distortion. If you have, however, the
> capability to put seriously more than 1Vpp into it (like 12V?) I don't
> know what happens.
>
> Another idea: have you checked the setting "MIC SEL" is still on LINE IN?
> I guess you do have acesss to the K3 Serial line, so you could use the
> K3 Utility to execute macros? Here is mine to switch to LINE IN:
> "MD2;MN053;UP;UP;MN255;"
> I did had problems with line out in the past, and Elecratf support
> digged out that it may be an equalizer setting issue for in and out.
> Try resetting the RX EQ to flat.
> 73 gl Gernot DF5RF
>
> Am 10.03.2020 um 00:50 schrieb Michael Tope:
>> Recently I've made some configuration changes at my remote station
>> that should in the end improve things. In the short term, however, it
>> has caused problems when working voice. Specifically I was getting
>> feedback if I raised the line out level on the PC too far past a
>> certain threshold which seem to depend on the K3 compressor settings
>> (in case you are wondering, yes, the K3 monitor level was set to 0).
>> Despite these problems, I was able to make some 40 meter SSB contacts
>> Sunday morning during the ARRL DX Phone contest.
>>
>> On Sunday afternoon, I connected to the remote with about ten minutes
>> to go in the contest and heard PY0F calling CQ on 20 meters with a
>> very loud signal. Not having touched the settings from the night
>> before, I figured I would tweak the tuning on the KAT-500 and then
>> just call him. Things did not go well. The rig broke into audio
>> feedback and I lost transmit/receive control for what seemed like a
>> forever, but was probably in reality only about 15 seconds.
>>
>> After I regained control of the rig, I power cycled the rig and then
>> power cycled the computer (I can do that remotely). The K3 still
>> works fine on CW, but I can no longer operate SSB. TeamViewer
>> indicates I am getting audio to the remote site, but the radio no
>> longer responds. I've tried both VOX and manually switching to
>> transmit. Either way, I get nothing. I even tried playing a local
>> audio source on the computer at the remote site which should have
>> gone straight into the K3. I still got nothing.
>>
>> IS IT POSSIBLE TO DAMAGE THE LINE INPUT OF THE K3 IF IT IS OVERDRIVEN
>> BY A SOUNDCARD LINE OUTPUT OR DOES THE K3 SOMEHOW SELF-PROTECT? IF
>> THE FORMER, WHAT PART IN THE K3 SERVES AS THE "FUSE"?
>>
>> I know it is premature to assume the K3 is damaged as I haven't
>> physically been to the remote site test the rig since the incident,
>> but I wanted to understand what the worst-case scenarios might look
>> like.
>>
>> Thanks & 73,
>>
>> Mike W4EF.................
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Don Wilhelm

Re: Possible K3 Line Input Damage

In reply to this post by Michael Tope

Mike,

This sound to me like you have to make a trip to the remote site to see
what is going on. A soundcard failure may have applied DC voltage to
the K3 and damaged it (but I have never heard of that happening).
You may have a soundcard failure of some sort and no audio is getting to
the K3 - so go to the site with another soundcard in hand to use if
necessary.

When testing with the new soundcard, if the Line In does not work, lower
the computer output of the soundcard and try Mic In (change the MIC SEL
menu). If that gets audio to the K3 while Line In does not, then
contact [hidden email] to see where you should go from that point.

73,
Don W3FPR

On 3/9/2020 7:50 PM, Michael Tope wrote:

> Recently I've made some configuration changes at my remote station that
> should in the end improve things. In the short term, however, it has
> caused problems when working voice. Specifically I was getting feedback
> if I raised the line out level on the PC too far past a certain
> threshold which seem to depend on the K3 compressor settings (in case
> you are wondering, yes, the K3 monitor level was set to 0). Despite
> these problems, I was able to make some 40 meter SSB contacts Sunday
> morning during the ARRL DX Phone contest.
>
> On Sunday afternoon, I connected to the remote with about ten minutes to
> go in the contest and heard PY0F calling CQ on 20 meters with a very
> loud signal. Not having touched the settings from the night before, I
> figured I would tweak the tuning on the KAT-500 and then just call him.
> Things did not go well. The rig broke into audio feedback and I lost
> transmit/receive control for what seemed like a forever, but was
> probably in reality only about 15 seconds.
>
> After I regained control of the rig, I power cycled the rig and then
> power cycled the computer (I can do that remotely). The K3 still works
> fine on CW, but I can no longer operate SSB. TeamViewer indicates I am
> getting audio to the remote site, but the radio no longer responds. I've
> tried both VOX and manually switching to transmit. Either way, I get
> nothing. I even tried playing a local audio source on the computer at
> the remote site which should have gone straight into the K3. I still got
> nothing.
>
> IS IT POSSIBLE TO DAMAGE THE LINE INPUT OF THE K3 IF IT IS OVERDRIVEN BY
> A SOUNDCARD LINE OUTPUT OR DOES THE K3 SOMEHOW SELF-PROTECT? IF THE
> FORMER, WHAT PART IN THE K3 SERVES AS THE "FUSE"?
>
> I know it is premature to assume the K3 is damaged as I haven't
> physically been to the remote site test the rig since the incident, but
> I wanted to understand what the worst-case scenarios might look like.
>